Resinous interpolymers



Patented July 5, .1949

UNITED STATES PATENT OFFICE BESINOUS INTERPOLYMERS David '1. Mom.Dayton, Ohio, assignor to Moncanto poration of Delaware ChemicalCompany, St. Louis, Mo., a cor- No Drawing. Application February 19,1945, Serial No. 578,794

8 Claims.

The present invention relates to new resinous interpolymerizationproducts.

An object of the present invention is to provide highly heat-resistant,readily moldable interpolymerization products of styrene.

I have found that valuable interpolymerization products may be obtainedby polymerizing styrene in the presence of benzalphthalide:

properties. My new styrene interpolymers in their clear and transparentform may be employed for the production of transparent objects such asWindshields and the like, or for transparent, molded articles, forelectrical insulating materials, etc. The excellent thermalstabllitjn-par- 2 continuous polymerization methods, stepwise additionof either of the two monomers, depending upon the rate at which they areconsumed, may be employed.

The interpolymerization may be eflected in the presence or absence ofcatalysts of polymerization. Suitable catalysts which may be used areticularly the high heat distortion point of the styrene-benzalphthalideinterpolymers makes them suitable for use in many fields where poly--styrene,- because of its lower heat distortion point, 1

cannot be used.

For the production or clear, transparent, resinous products I prefer toemploymixtures of monomeric styrene and benzalphthalide in which mix,-turesthe benzalphthalide content is below approximately 1:1 mole ratio(65% by weight,benzalphthalide) and preferably below 50% by weight ofsaid mixture. Improvement oi polystyrene is apparent even with as littleas 0.1% by weight benzalphthalide in the ,interpolymer, althoughgenerally somewhat more is usually employed. Polymerizatlonlof themixtures may be effected by any of theknown polymerizing methods. forexample,by polymerization in mass, in solution, in a liquid which isa-solvent for the monomer mixture and a non-solvent for theinterpolymer, in aqueous dispersion or in emulsion. Solvents such asdioxane and carbon tetrachloride dissolve both the monomers as well asthe interpolymer. Solvents such as the lower aliphatic alcohols dissolvethe monomers, whereas theinterpolymeris benzoyl peroxide, acetylperoxide, tertiary butyl hydroperoxide. Potassium or ammoniumpersulfates may be employed for emulsion polymerization. Temperatures offrom, say, C. to 125 6., depending upon the presence or absence ofcatalysts are generally employed.

The present invention is further illustrated, but

not limited, by the following examples:

Example 1 A mixturefconsisting of 80 parts by we sht 0i styrene and 20parts by weight of ben'zalphthalide was mass polymerized, in the absenceof a catalyst, by heating at a temperature of 70 for 8 days and'then ata temperature of 100C. for 5 days. The resulting hard product had analcohol soluble content of 9.6%. The interpolymer .was'

purified by dissolving in dioxane and precipitation in alcohol. Thepurified material had a soften- .ing point M140" 0., a melting p'oint'o!225 0,

and a decomposition point of 250 C., as deter-- mined on the copperMaquenne bar. Theprode uct thus obtained was a flufiy, white powder,which was compression molded in a steel die em; ploying the followingconditions:

1 Temperature 9C).... Pressure P. S. L- 2500 Time minutes.'.

insoluble therein.' Accordingly, when the interpolymer is produced insolution in a solvent in which it is soluble. it may be recoveredtherefrom by pouring the solution of polymer into an alcohol such' asmethanol, ethanol or isopropanol. In

in the American Testing Materials Book of Standards for 1942 on page1060.

For purposes of comparison, styrene, alone, was

subjected to the same polymerizing conditions employed for thepreparation of the above copolymer. The product had a heat-distortionpoint of only 76 C.

The stability to heating of the present interpolymer was furtherillustrated by the i'ollowing experiment:

The compression molded specimen used above for the determination of heatdistortion point was comminuted and the comminuted was no perceptibledistortion of the molded speeimen.

Example 2 A mixture consisting of 10 parts by weight of benzalphthalideand 90 parts by weight of styrene was subjected to the polymerizationconditions described in Example 1. The hard, resinous product thusobtained had an alcohol soluble content of 4.6%. Solvent purification ofthe product by solution in dioxane and precipitation from alcohol gave awhite, powdery interpolymer having a softening point of 130 C., amelting point of 215 C. and a decomposition point of over 250 C. Acompression molded test specimen gave a heat distortion point of 93 C.

The interpolymer was soluble in benzene, dioxane, chloroform and ethylacetate, insoluble in acetone and somewhat softened by gasoline.

The molded test specimen was boiled for 3 hours in a 10% aqueoussolution of sodium hydroxide and then allowed to stand in the alkalinesolution for 18 hours. At the end of that time there was no sign ofeither distortion or surface crazing. Thus, substantially no hydrolysisof the molded piece occurs in boiling alkali.

Example 3 A mixture consisting of 30 parts by weight of benzalphthalideand 70 parts by weight of styrene was subjected to polymerizationemploying the conditions described in Example 1. The hard, resinousmaterial thus obtained had an alcoholsoluble content of 14.7%. Solventpurification was carried out by dissolving the hard resin in dioxane andprecipitating the interpolymer by pouring the solution into alcohol. Thewhite, powdery interpolymer thus obtained had a softening point of 145C., a melting point of 230 C. and a decomposition point of over 250 C.,as determined on the copper Maquenne bar. Evaluation of a compressionmolded test specimen gave a heat distortion point of 106.5 C.

The molded object was clear and colorless. It was not affected byimmersion in hot dilute alkali or boiling water for long periods oftime.

Example 4 A mixture consisting of 30. g. of benzalphthalide, 270 g. ofstyrene, 700 mi. of water, 3.5 g. of soap flakes and 0.5 g. of potassiumpersulfate was heated slowly during a time of onehalf hour to atemperature of 90 C. and maintained at approximately that temperaturefor about 18 hours. Mechanical stirring was employed during this entireperiod. The resulting emulsion of polymeric material was poured intoalcohol and precipitated by treatment with dilute aqueous sodiumchloride. Upon filtration, washing and drying there was obtained awhite, powdery interpolymer having an alcohol-soluble content of 0.1%, asoftening point of 140 C., a melting point of 210 C. and a decompositionpoint of 250 C. Compression molded test specimens of the interpolymerhad'a heat distortion point of 92C.

4 Interpolymers of styrene and benzalphthalide containing below, say,50% of benzalphthalide may be injection molded by the ordinary injectionmolding technique, interpolymers containing between 5% and 30% by weightof benzalphthalide being particularly suitable for injection moldingoperations.

when injection molding the herein described interpolymers it has beenfound that the temperature for molding does not differ materially fromthat employed when molding polystyrene. For example, an interpolymerprepared from a mixture consisting of 20 parts by weight of benzal;

Q phthalide and 80 parts by weight of styrene compares with the moldingtemperature of polystyrene as follows:

interpolymer Polystyrene F. F. 0 linder temperature 400 400-450 oldtemperature Although the heat distortion value of the interpolymer isconsiderably higher than for polystyrene, actually the moldingconditions are no more severe than are those employed for polystyrene.

Because of the excellent thermal and physical properties of the presentinterpolymers they are valuable for the production of extruded, cast ormolded parts for the following purposes:

Electrical insulation, particularly ignition and lighting fixtures forautomotive and aeronautical purposes, also switches, sockets, lamphousings, commutators, telephone parts, such as hand sets and bases,flashlight cases, lampshades, vacuum cleaners, electrical shavers,refrigerator parts, hair dryers, rectifiers, transformers, rheostats,voltage regulators, etc., steering wheels, decorative parts, knobs andhandles, radio parts, such as molded cases, plugs, adapters, coil forms,coaxial cable spacers, condensers, panel boards, high frequencylead-ins, antenna loops and bases, dental and surgical instruments anddentures, printing plates, photographic films, trays, s'pinnerets andspinning buckets, travelers, thread guides and shuttles for weaving andspinning, pumps, chemical tank lining material, gaskets, opticalinstruments and accessories.

Cast objects may be readily made by pouring the monomeric mixture or thepartially polymerized viscous syrup into molds and carrying thepolymerization to completion within the molds. When employed as animpregnating agent, for example, in the preparation of insulating tape,the tape may be impregnated with either the mixture of monomers or apartially polymerized syrup and polymerization subsequently carried outto completion in situ. A partially polymerized viscous syrup may also beadvantageously employed in the manufacture of laminates.

For certain purposes the interpolymers may be drawn or extruded intothreads or filaments. Fibrous material may be obtained by atomizingsolutions of these resins in volatile solvents, under conditions wherebythe solvent is evaporated and the fiber recovered in dry, fibrous form.Such material serves as an ideal heat and electrical insulator. a 4

A variety of methods may be utilized in applying the principle ofmyinvention, and the products produced thereby, the invention beinglimited only by the appended claims.

percent benzalphthalide and from 99.9 percent to 35 percent of styrene,and heating at a temperature between 40 C. and 125 0., until a solidresinous composition is obtained.

3. The process of preparing solid copolymers which comprises mixing frompercent to 30 percent benzalphthalide and from 95 percent to '70 percentof styrene, and heating the mixture between 40' C. and 125 C., in thepresence of a tion is obtained.

4. The process of preparing solid copolymerswhich comprises mixing from5 percent to percent benzalphthalide and from 95 percent to '70 percentof styrene, and heating at a temperature between 40 C. and 125 C., untila solid resinous composition is obtained.

5. A copolymer having heat distortion point in excess of that possessedby polystyrene, being copolymers of 0.1 percent to percent ofbenzalphthalide and from 99.9 percent to 35 percent of styrene.

6. A copolyrner having heat distortion point in excessof that possessedby polystyrene, being copolymers of 5 percent to 30 percent ofbenzalphthalide and from percent to '10 percent of styrene.

DAVID T. MOWRY.

No references cited.

